Monday, November 29, 2021
Menu

News

Under Pressure—Barotrauma in Skydiving

Under Pressure—Barotrauma in Skydiving

By Laura Galdamez, M.D.

Safety & Training
Wednesday, June 16, 2021

Barotrauma is injury that occurs as a direct result of changes in ambient pressure. Boyles Law states that at constant temperature, a volume of a gas is inversely proportional to the ambient pressure. As ambient pressure decreases, the volume of gas increases (e.g., with increasing altitude). Sea-level ambient pressure is 29.92mmHg (millimeters of mercury) or 1atm (standard atmosphere), but on top of Mt. Kilimanjaro at an altitude of 19,000 feet, ambient pressure is reduced by 50% and the volume of that air has doubled.

Barotrauma is one of the most common medical problems associated with air travel. Military HALO clinics frequently treat barotrauma injuries including ruptures of the ear’s tympanic membrane, sinus blocks and barodontalgia, also known as “tooth squeeze.” While the true incidence of barotrauma is unknown, a random survey documented approximately 65% of children and 46% of adults have experienced discomfort or pain related to barotrauma during commercial air flights. Now, before you say, “But those commercial flights fly much higher than we do when skydiving,” remember that those flights are pressurized to the equivalent altitude of roughly 8,000 feet.

A study out of DeLand, Florida, polled skydivers and found that about 19% of respondents reported middle-ear symptoms after descent. Skydivers’ middle-ear pressures were measured before and after jumping. There was a significant difference in the before/after values that correlated well with those who were/were not able to equalize pressure, but did not necessarily correlate with symptoms reported by the skydivers.

Types of Barotrauma

Middle-ear barotrauma is one of the most commonly reported and described injuries. The middle ear is actually a small, air-filled chamber holding the tiny bones required for hearing, enclosed by the tympanic membrane and inner-ear round window (see Figure 1). The middle ear connects to the outside environment via the Eustachian tube (ET), a small channel that drains near the back of the throat.

During ascent, as air pressure decreases, a difference of 15mmHg pressure between the middle-ear cavity and atmospheric pressure will cause the functioning ET to spontaneously open at the back of the throat to release expanding air pressure within the middle ear. This happens every 400 feet (122 meters) or so. Conversely, during descent, the increasing atmospheric pressure and decreasing pressure in the middle ear causes contraction and compression of the ET, which prevents air from entering the middle ear to equalize the pressure difference. This is why middle ear barotrauma is far more common during descent.

Diagram by Brockmann Chittka.

The sensation of ear fullness, discomfort, muffled hearing and dizziness can occur with a pressure difference of 60mmHg. If the pressure difference is significantly greater in one ear, severe dizziness can occur and lead to a loss of situational awareness.

Tactics can be used to force the ET open (discussed later) and equalize the pressure in the middle ear, but this becomes more difficult as the pressure differential increases. Eventually, the soft end of the ET at the back of the throat will close off with such force (ET lock) that further attempts to equalize the inner-ear negative pressure are futile and may worsen the situation.

Pressure differentials greater than 100-500mmHg can cause tympanic-membrane rupture, hearing loss, dizziness and vomiting. Patients will report sudden pain relief with some fluid drainage from the ear canal. The pressure differentials that cause the ET lock and membrane ruptures to occur will vary from person to person. Of 31 South African skydivers surveyed, 12 reported tympanic-membrane rupture due to skydiving.

The inner-ear window can also rupture upon descent due to the pressure differential and typically results in sudden hearing loss, dizziness, imbalance and vomiting. This negative pressure in the middle ear can also cause small blood vessels to burst, creating blood buildup in the middle ear, leading to similar symptoms.

Sinus barotrauma can occur on both ascent and descent. Sinus squeeze occurs on descent, resulting from air molecules contracting (reducing volume) within the open sinus, primarily the frontal sinus due to its long, fragile connecting duct. This results in facial pain, headache and nausea. Nosebleed may occur due to rupture of the small blood vessels in the sinuses. Reverse squeeze of the sinus can occur during ascent as air expands, causing increased sinus pressure and facial pain. 

Barodontalgia is tooth pain or sensitivity that can occur while flying due expansion of air inside fillings, caps, crowns, root canals or inflamed pulp. This can result in dental-work damage or rupture of the tooth’s mucosa. However, it is extremely rare with an incidence of only 0.26% in a high-altitude flight study. Chronic gum infection and inflammation was the most common underlying risk factor.

And, the last air-filled human organ … we all knew this was coming … the gut. Well, air in the intestines expands like it does in any other gas-filled structure and can cause bloating, cramping, distension and pain during ascent. Should the discomfort become intolerable, there is only one way to relieve the pain ... release the gas. Oh my! However, you can help avoid this situation and make yourself (and your sky buddies) more comfortable at 14,000 feet. Avoid foods that increase gas formation at least 24 hours before your planned skydive. Foods most often linked to intestinal gas include:

  • Beans and lentils
  • Asparagus, broccoli, Brussels sprouts, cabbage and other vegetables
  • Fructose, a natural sugar found in artichokes, onions, pears, wheat and some soft drinks
  • Lactose, the natural sugar found in milk
  • Fruits, oat bran, peas, and other foods high in soluble fiber
  • Corn, pasta, potatoes and other foods rich in starch
  • Sorbitol, the artificial sweetener
  • Whole grains, such as brown rice, oatmeal, and whole wheat

This list covers a lot of healthy food, but you don’t have to severely restrict your diet. Most likely just having too many of these foods will result in excessive gas.

Predisposing Factors

There are no clear predictive tests to determine who will be affected by barotrauma. Eustachian-tube imaging, tympanic-membrane and ear-structure evaluation do not predict those more at risk. However, documented risk factors do include upper respiratory tract infections, allergies, new or chronic middle-ear infections, nasal polyps, sinus infections, enlarged nasal turbinates, septal deviation, chronic middle-ear/nose/throat disease, pregnancy and previous ET dysfunction. Previous episodes of barotrauma can predispose a jumper to further injury, as each event causes mucous membrane swelling and deterioration that further compromises the system anatomy. Therefore, one attack makes another more likely. Delayed ear pain is more common in older individuals, likely secondary to having stiffer ETs.

In addition, the severity of barotrauma appears directly related to the rate of descent from altitude, which in skydiving is relatively rapid and not modifiable.

Prevention and Treatment

Now that I know what it is … what is the best way to avoid barotrauma?
Don’t go skydiving. Wait, that’s too extreme! But, do avoid skydiving if you have an upper- respiratory infection, significant allergy symptoms, are within 24 hours of dental treatment requiring anesthetics or are within seven days following any surgery.

Best evidence currently supports using decongestants to minimize middle-ear barotrauma. Oral decongestants (e.g., pseudoephedrine, phenylephinrine and antihistamines such as loratidine, cetirizine and diphenhydramine) appear to be more effective than topical medications (oxymetazoline or fluticasone). Pseudoephedrine (Sudafed in the U.S.) currently has the best evidence for success. A dose of 120mg at least 30 minutes before flying/skydiving has shown to reduce mucous-membrane swelling and decrease ear pain.

Anti-inflammatories like ibuprofen (Advil, Motrin) will reduce inflammation of the mucous membranes, as well. Antihistamines in general don’t have great evidence for success and can cause drowsiness and mental fogginess, not an ideal combination for skydiving.

Resistant cases may require surgical procedures such as myringotomy, a laser Eustachian tuboplasty to improve ET function or sinus surgery to re-establish good drainage and ventilation of the affected sinus.

I seem to have ear pain frequently when skydiving, what can I do to minimize effects and continue jumping?

The next best way to avoid barotrauma is to frequently equalize the air pressure with the middle ear and avoid a pressure differential from building up. There are a few methods to choose from, including yawning and swallowing with your nose plugged. The Valsalva maneuver involves pinching your nose and blowing, but can cause dizziness and even irregular heart rhythms in some people. The Frenzel maneuver involves thrusting your jaw forward and trying to say ‘K’ repeatedly while closing the nose, mouth and throat (like when preparing to lift a heavy weight). This maneuver is better for those who become symptomatic from Valsalva. For resistant cases, several devices are available to help equalize pressure upon landing. The Eustachi is a small device that is inserted into one nostril and blows air into the nose while the patient swallows to help open the ET. The Otovent requires the patient to inflate a balloon with their nose, then allow it to deflate and push air back into the nose while swallowing water. This device has been shown to reduce middle-ear pressures better than the Valsalva maneuver alone. Pressure-equalizing earplugs use filters to help regulate air-pressure change in the ear canal, allowing for a more gradual change. However, there was no effect on middle-ear pressures or symptoms in volunteers that used them on an ascent to 8,000 feet, and they actually led to somewhat worse outcomes.

 

So … I jumped anyway and ruptured my tympanic membrane, now what?
The good news is that most tympanic-membrane ruptures will heal naturally, with no need for special antibiotics or steroid ear drops. In fact, don’t put anything into your ear! I have seen more than one person permanently lose their hearing from an eardrop they thought “might help.” Most ear drops are meant for the outer ear canal only, and can permanently damage middle- or inner-ear structures. Keep your ear completely dry. When taking a shower, use a tight earplug, putty or a cotton ball with Vaseline to keep water out of the affected ear. You should make an appointment with an ENT doctor, as there may be additional injury to the inner-ear membrane that might require surgery to prevent permanent structural changes, such as fistula formation.

Although barotrauma is common and can be debilitating, steps can be taken to prevent and treat it. So, keep on jumping smart and safe, and don’t let the pressure get to you!


About the Author

Laura Galdamez, M.D., B-53870, began skydiving in early 2020. She works as an emergency medicine physician in Houston, Texas; is a Fellow of the Academy of Wilderness Medicine; and worked on the medical team for Alan Eustace’s StratEx high-altitude balloon mission.

Print
Categories: Safety & Training   |   Rate this article:
4.8
  |  Number of views: 4027   |  Comments: 0

Leave a comment

This form collects your name, email, IP address and content so that we can keep track of the comments placed on the website. For more info check our Privacy Policy and Terms Of Use where you will get more info on where, how and why we store your data.
Add comment